While this one seems like an official Google project, some other projects are not, even if it is on github.com/google

A random example E.g https://github.com/google/filament#disclaimer

This is not an officially supported Google product.

Fair enough, I missed that specific line. The point still stands that I wouldn't expect this to have GDM leadership backing. (If you're planning to use this at all, that matters for how much faith you should have in the product.)

it's built on top of https://github.com/agent-substrate/substrate which is not on Google github.